When Apple Inc.’s iPhone 5 was unveiled with great fanfare Wednesday, the two-hour presentation highlighted a wide range of new and optimized services, including a cloud-based iTunes music service, a faster processor, and access to high-speed 4G LTE networks.

Although these new features will undoubtedly make the device more appealing, they also have the potential to boost its data usage.

“Smartphones are already huge consumers of data, and the iPhone 5 is likely to increase that usage,” said Mike Gikas, senior editor at Consumer Reports, the nonprofit consumer publication. “Apple, like other phone makers, keeps coming up with more compelling reasons to use data.”

Gikas said that cloud-based services and apps, are “like little vampires that keep sucking data even when you don’t think they are. They are always updating themselves, connecting to the cloud. That’s all data usage.”

Wireless carriers have responded by reorganizing their consumers’ plans around data packages, often offering voice and texting on an unlimited basis. One new thing is shared service plans, where a family with multiple devices — iPhones, Android phones, and tablets — shares a budgeted amount of data, such as 2 gigabytes a month.

This means consumers will need to learn just how much space those music, picture, and movie downloads take up. Prior to the new generation of super-fast 4G LTE-capable phones, consumers wildly overestimated how much data they would use in a typical month, and overpaid for service, according to a study last year by the Citizens Utility Board in Chicago, a utility watchdog group.

“Wireless carriers were pushing people to shop at the Big and Tall store for data,” said spokesman Jim Chilsen. “People were paying for bloated plans that they didn’t need.”

‘Consumers . . . are going to have to start looking more closely at the data plans.’

Now, though, if you buy the iPhone 5 or another phone that runs on the speedy 4G LTE cellular network, such as the HTC Thunderbolt, expect your data usage to ramp up considerably, and buy accordingly. For example, owners of non-4G smartphones used an average of 500 megabytes of data a month so far this year, according to a study by Validas LLC, which makes software that analyzes wireless phone consumption and bills. However, owners of 4G LTE phones typically used more than double that amount a month: 1.2 gigabytes.

“It makes you wonder what’s going to happen with the iPhone 5,” said Dylan Breslin-Barnhart, of Validas, based in Sugar Land, Texas, outside Houston.

With download speeds that are as much as 10 times faster than the current 3G standard, 4G LTE enables a new level of mobile experience: HD video is easily downloadable from the back of a cab, video chats are smoother, graphic-rich presentations can be swapped mid-meeting. The mobile experience is richer, more vivid — and uses much more data.

For rough measure, 1 megabyte of data is equal to about 50 e-mails without attachments, viewing six Web pages, or streaming two minutes of music. So 1 gigabyte, roughly 1,000 megabytes, is equivalent to 50,000 e-mails without attachment, streaming 33 hours of music, or viewing 5,600 Web pages.

The new monthly plans by the carriers differ in price and features. AT&T Wireless and Verizon Wireless, for example, charge for each device: $40 for a smartphone, $10 for a tablet. Each carrier then sells a chunk of data: 4 gigabytes is $70 a month at both companies. Both plans offer unlimited voice calls and text-messaging.

T-Mobile starts its data plans at 2 gigabytes per phone, rather than offering a total that a family can share among devices. Voice calls and text-messaging are unlimited.

At Sprint all data plans include unlimited data and text-messaging, but it charges for voice minutes in packages. Each carrier has a separate plan for tablets.

The variations get even more daunting when you add “prepaid” smartphone services to the mix, which do not require service contracts, such as the typical two-year lockup offered by the main carriers. In prepaid plans, though, the smartphone typically costs much more.

The adjustment to the new way of buying phone service could be rough for consumers who have just barely mastered the complicated task of calculating voice minutes and text-messaging bundles.

“Consumers who once focused on voice minutes and text messages are going to have to start looking more closely at the data plans,” said Gikas, the Consumer Reports editor.